Cmd.exe

Cmd.exe
Command Prompt, also known as cmd.exe or cmd, is the default command-line interpreter for the OS/2, eComStation, ArcaOS, Microsoft Windows (Windows NT family and Windows CE family), and ReactOS operating systems. On Windows CE .NET 4.2, Windows CE 5.0 and Windows Embedded CE 6.0 it is referred to as the Command Processor Shell. Its implementations differ between operating systems, but the behavior and basic set of commands are consistent. is the counterpart of in DOS and Windows 9x systems, and analogous to the Unix shells used on Unix-like systems. The initial version of for Windows NT was developed by Therese Stowell. Windows CE 2.11 was the first embedded Windows release to support a console and a Windows CE version of . The ReactOS implementation of is derived from FreeCOM, the FreeDOS command line interpreter.
Operation
interacts with the user through a command-line interface. On Windows, this interface is implemented through the Win32 console. may take advantage of features available to native programs of its own platform. For example, on OS/2 and Windows, it can use real pipes in command pipelines, allowing both sides of the pipeline to run concurrently. As a result, it is possible to redirect the standard error stream. (uses temporary files, and runs the two sides serially, one after the other.)
Multiple commands can be processed in a single command line using the command separator .
When using this separator in the Windows , each command must complete successfully for the following commands to execute. For example:
C:\>CommandA && CommandB && CommandC
In the above example, will only execute if completes successfully, and the execution of depends on the successful completion of . To process subsequent commands even if the previous command produces an error, the command separator should be used. For example:C:\>CommandA & CommandB & CommandC
On Windows XP or later, the maximum length of the string that can be used at the command prompt is 8191 characters. On earlier versions, such as Windows 2000 or Windows NT 4.0, the maximum length of the string is 2047 characters. This limit includes the command line, individual environment variables that are inherited by other processes, and all environment variable expansions.
Quotation marks are required for the following special characters:
& < > [ ] { } ^ = ; ! ' + , ` ~ [white space]
Internal commands
OS/2
The following is a list of the Microsoft OS/2 internal commands:
break
chcp
cd
chdir
cls
copy
date
del
detach
dir
dpath
echo
erase
exit
for
goto
if
md
mkdir
path
pause
prompt
rd
rem
ren
rename
rmdir
set
shift
start
time
type
ver
verify
vol
Windows NT family
The following list of internal commands is supported by on Windows NT and later:
assoc
break
call
cd
chdir
cls
color
copy
date
del
dir
dpath
echo
endlocal
erase
exit
for
ftype
goto
if
keys
md
mkdir
mklink (introduced in Windows Vista)
move
path
pause
popd
prompt
pushd
rd
rem
ren
rename
rmdir
set
setlocal
shift
start
time
title
type
ver
verify
vol
Windows CE
The following list of commands is supported by on Windows CE .NET 4.2, Windows CE 5.0 and Windows Embedded CE 6.0:
attrib
call
cd
chdir
cls
copy
date
del
dir
echo
erase
exit
goto
help
if
md
mkdir
move
path
pause
prompt
pwd
rd
rem
ren
rename
rmdir
set
shift
start
time
title
type
In addition, the command is available as an external command stored in .
ReactOS
The ReactOS implementation includes the following internal commands:
?
alias
assoc
beep
call
cd
chdir
choice
cls
color
copy
ctty
date
del
delete
delay
dir
dirs
echo
echos
endlocal
erase
exit
for
free
goto
history
if
memory
md
mkdir
mklink
move
path
pause
popd
prompt
pushd
rd
rmdir
rem
ren
rename
replace
screen
set
setlocal
shift
start
time
timer
title
type
ver
verify
vol
Comparison with COMMAND.COM
On Windows, is mostly compatible with but provides the following extensions over it:
More detailed error messages than the blanket "Bad command or file name" (in the case of malformed commands) of . In OS/2, errors are reported in the chosen language of the system, their text being taken from the system message files. The command can then be issued with the error message number to obtain further information.
Supports using of arrow keys to scroll through command history. (Under DOS this function was only available under DR DOS (through HISTORY) and later via an external component called .)
Adds rotating command-line completion for file and folder paths, where the user can cycle through results for the prefix using the , and for reverse direction.
Treats the caret character as the escape character; the character following it is to be taken literally. There are special characters in and (e.g. "", "" and "|") that are meant to alter the behavior of the command line processor. The caret character forces the command line processor to interpret them literally.
Supports delayed variable expansion with , allowing values of variables to be calculated at runtime instead of during parsing of script before execution (Windows 2000 and later), fixing DOS idioms that made using control structures hard and complex. The extensions can be disabled, providing a stricter compatibility mode.
Internal commands have also been improved:
The command was merged into the command, as part of its switch.
and commands limit the scope of changes to the environment. Changes made to the command line environment after commands are local to the batch file. command restores the previous settings.
The command allows subroutines within batch file. The command in only supports calling external batch files.
File name parser extensions to the command are comparable with C shell.
The command can perform expression evaluation.
An expansion of the command supports parsing files and arbitrary sets in addition to file names.
The new and commands provide access past navigated paths similar to "forward" and "back" buttons in a web browser or File Explorer.
The conditional command can perform case-insensitive comparisons and numeric equality and inequality comparisons in addition to case-sensitive string comparisons. (This was available in DR-DOS, but not in PC DOS or MS-DOS.)
See also
Comparison of command shells
List of DOS commands
COMMAND.COM
PowerShell
Windows Terminal
References
Further reading
External links
Command shells
OS/2 command shells
Windows command shells
OS/2 commands
OS/2 files
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